Device for controlling hybrid vehicle

Abstract

A hybrid vehicle control device includes an engine, a motor/generator, an automatic transmission in which the gear ratio can be fixed by the driver's intention; and a drive wheel. The control device has an assist traveling mode and an engine generation traveling mode as hybrid modes in which the engine and the motor/generator are drive sources. The control device includes a rotational speed limit setting unit which sets a value that exceeds the upper rotational speed limit, at which the motor/generator can carry out a torque output, as the rotational speed limit of the engine motor rotational speed, and a rotational speed limit control unit for reducing the rotational speed limit to the rotational speed limit at which the motor/generator can carry out a torque output, when the engine motor rotational speed has reached the rotational speed limit and there is a torque output request of the motor/generator.

The invention claimed is: 
     
       1. A hybrid vehicle drive system comprising:
 an engine; 
 a motor/generator connected to the engine and connected to a battery that carries out charging/ discharging; 
 a transmission connected to the motor/generator, in which a gear ratio can be fixed by a driver's input; 
 a drive wheel connected to the transmission; and 
 a controller programmed to selectively set an assist traveling mode in which the motor/generator generates a drive torque, and an engine generation traveling mode in which the motor/generator generates a power generation torque, as hybrid modes in which the engine and the motor/generator are drive sources, 
 the controller being programmed to include:
 a rotational speed limit setting unit programmed to set a value that exceeds an upper rotational speed, at which the motor/generator can generate a requested torque, as a rotational speed limit of the motor/generator, and 
 a rotational speed limit control unit programmed to reduce the rotational speed limit to the upper rotational speed at which the motor/generator can generate the requested torque, when a rotational speed of the motor/generator has reached the rotational speed limit, and a request for the requested torque of the motor/generator exists, during the assist traveling mode in a state in which the gear ratio is fixed by the driver's input, 
 the requested torque being a requested drive torque or a requested power generation torque. 
 
 
     
     
       2. The hybrid vehicle drive system according to  claim 1 , wherein
 the rotational speed limit control unit is programmed to further reduce the rotational speed limit as an energy storage requirement with respect to the battery is increased. 
 
     
     
       3. The hybrid vehicle drive system according to  claim 2 , wherein
 the rotational speed limit control unit is programmed to determine the energy storage requirement to increase as an auxiliary machine power consumption, which is consumed by a plurality of auxiliary machines provided to a vehicle, is increased. 
 
     
     
       4. The hybrid vehicle drive system according to  claim 3 , wherein
 the rotational speed limit control unit is programmed to determine the energy storage requirement to increase as a charge capacity of the battery is reduced. 
 
     
     
       5. The hybrid vehicle drive system according to  claim 2 , wherein
 the rotational speed limit control unit is programmed to determine the energy storage requirement to increase as a charge capacity of the battery is reduced. 
 
     
     
       6. The hybrid vehicle drive system according to  claim 2 , wherein
 the rotational speed limit control unit is programmed to determine an execution timing for reducing the rotational speed limit in accordance with an energy storage requirement with respect to the battery. 
 
     
     
       7. The hybrid vehicle drive system according to  claim 6 , wherein
 the energy storage requirement is at least the charge capacity of the battery. 
 
     
     
       8. The hybrid vehicle drive system according to  claim 6 , wherein
 the rotational speed limit control unit is programmed to delay the execution timing more as a driver's acceleration request becomes greater. 
 
     
     
       9. The hybrid vehicle drive system according to  claim 2 , wherein
 the rotational speed limit control unit is programmed to restore the rotational speed limit to the rotational speed limit which is set by the rotational speed limit setting unit, when a deviation condition is met, in which the rotational speed of the motor/generator deviates from a reduced rotational speed limit. 
 
     
     
       10. The hybrid vehicle drive system according to  claim 9 , wherein
 the rotational speed limit control unit is programmed to set an occurrence of the rotational speed of the motor/generator being reduced to equal to or less than a predetermined value as the deviation condition. 
 
     
     
       11. The hybrid vehicle drive system according to  claim 2 , wherein
 the rotational speed limit control unit is programmed to restore the rotational speed limit to the rotational speed limit which is set by the rotational speed limit setting unit, when a driver's acceleration input is determined to exceed a second predetermined value. 
 
     
     
       12. The hybrid vehicle drive system according to  claim 1 , wherein
 the rotational speed limit control unit is programmed to determine an execution timing for reducing the rotational speed limit in accordance with an energy storage requirement with respect to the battery. 
 
     
     
       13. The hybrid vehicle drive system according to  claim 12 , wherein
 the energy storage requirement is at least the charge capacity of the battery. 
 
     
     
       14. The hybrid vehicle drive system according to  claim 12 , wherein
 the rotational speed limit control unit is programmed to delay the execution timing more as a driver's acceleration request becomes greater. 
 
     
     
       15. The hybrid vehicle drive system according to  claim 1 , wherein
 the rotational speed limit control unit is programmed to restore the rotational speed limit to the rotational speed limit which is set by the rotational speed limit setting unit, when a deviation condition is met, in which the rotational speed of the motor/generator deviates from a reduced rotational speed limit. 
 
     
     
       16. The hybrid vehicle drive system according to  claim 15 , wherein
 the rotational speed limit control unit is programmed to set an occurrence of the rotational speed of the motor/generator being reduced to equal to or less than a predetermined value as the deviation condition. 
 
     
     
       17. The hybrid vehicle drive system according to  claim 1 , wherein
 the rotational speed limit control unit is programmed to restore the rotational speed limit to the rotational speed limit which is set by the rotational speed limit setting unit, when a driver's acceleration input is determined to exceed a second predetermined value.